This invention relates to milling cutters for cutting profile shapes. It is particularly concerned with milling cutters that are provided with replaceable cutting inserts.
It is known to rough-cut a profile shape with a milling cutter that carries a series of replaceable cutting inserts. These inserts are preformed, typically by sintering, and have parallelogramic top faces so as to be reversible on the cutter. The inserts are mounted in positions such that their active cutting edges sweep a series of overlapping surfaces of revolution and rough out the profile shape as a series of mutually inclined portions. Finish machining is then necessary to obtain a smooth profile.
A similar milling cutter has been proposed as a gear hob (GB 1597599) in which a series of reversible cutting inserts are secured to successive teeth of a cutter disc, the inserts being mainly rectangular but at the radially outer tips of the teeth there being circular inserts or inserts with a bulbous curved cutting edge to relieve the gear tooth roots. In order to cut the involute gear tooth profile, of course, the rotation of the cutter must be coordinated with an indexing motion of the gear being cut. Furthermore, although the document suggests that the cutter can hob gear teeth to a finish quality, the trueness of the profile is plainly limited because finish grinding is recommended for heavy duty gears.